Is Joshua 20:1-6 condoning manslaughter?

When someone had carelessly but non-maliciously killed someone, then God’s Old Testament law made provision for him to escape capital punishment, whilst not trivialising the killing. There was no expensive prison infrastructure. So banishing someone within the land of Israel to a city of refuge was a practical humane solution.

This was not condoning manslaughter; it was recognition that the punishment should suit the crime.